Saponifikaation

Saponification is a chemical reaction in which esters, most commonly triglycerides found in fats and oils, are hydrolyzed in the presence of a base to yield glycerol and fatty acid salts, collectively known as soap. In practical terms, fats or oils react with alkali such as sodium hydroxide (NaOH) or potassium hydroxide (KOH) to form glycerol and fatty acid salts (sodium or potassium soaps).

The typical reaction can be written as: triglyceride + 3 NaOH → glycerol + 3 RCOONa (for sodium soap). Using KOH instead of NaOH yields soap of the potassium salts, which forms softer or liquid soaps. The reaction is base-catalyzed and occurs in aqueous or mixed phases; it is exothermic and often performed at elevated temperature to speed up the process.

Soapmaking can follow cold or hot processes. In cold process, a lye-water solution is mixed with fats and allowed to saponify and cure over time, producing a solid bar. In hot processes, heat is applied to accelerate saponification. The exact amounts of alkali depend on the fat’s composition and the desired soap, and are commonly described by the saponification value, which indicates how much alkali is needed to saponify a given weight of fat.

Applications include the production of household soaps and detergents, industrial cleaners, and specialty soaps. The byproduct glycerol (glycerin) has commercial value. Safety concerns center on the caustic nature of the reagents (lye) and the exothermic reaction, requiring proper handling and ventilation.

Historically, saponification has been practiced since ancient times and remains a foundational process in soap manufacture and related industries.